The present invention relates to an oil pump that is used as a driving source of a power steering apparatus for vehicles, and a method of assembling the oil pump.
Japanese Patent Application First Publication No. 2002-155872 (corresponding to U.S. Pat. No. 6,568,930) discloses an oil pump that is applied to a power steering apparatus for vehicles. The oil pump of the conventional art includes a pump housing with an annular recess, a cup-shaped cover member opposed to the pump housing, and a rotation shaft that extends through the cover member into the pump housing and is rotatably supported by the pump housing. A cam ring is disposed within an inside space that is defined by the cover member and the pump housing. A pump element constituted of an outer rotor with inner teeth and an inner rotor with outer teeth is rotatably disposed inside of the cam ring. An adjusting device for adjusting a radial gap or clearance between the inner teeth of the outer rotor and the outer teeth of the inner rotor is disposed at a connecting portion of the pump housing and the cover member. The adjusting device includes a groove formed at the connecting portion of the pump housing and the cover member, and an adjusting element that is disposed in the groove and constructed to project from the groove and retreat thereinto in a radial direction of the cam ring. The adjusting element has one end portion fixed to the cam ring. When the adjusting element moves in the radially inward direction of the cam ring so as to project from the groove, the adjusting element presses the cam ring such that the cam ring and the outer rotor are moved in the radially inward direction and thereby the clearance between the inner teeth of the outer rotor and the outer teeth of the inner rotor is adjusted. The thus-constructed oil pump of the conventional art aims to provide the clearance between the inner teeth of the outer rotor and the outer teeth of the inner rotor with accuracy.